3098 Insects. 



other obvious advantages. In this method of observing objects the minute ridges are 

 rendered clearly visible by means of their shadows. But in order to view certain ob- 

 jects in the most advantageous manner, it is desirable to get rid of the shadow 

 entirely, and this, as well as a far more brilliant illumination, is effected by the para- 

 bolic condenser constructed by Mr. Wenham, which is fully described in a late part 

 of the Society's ' Transactions.' There are, however, certain practical difficulties in 

 constructing a paraboloid correctly, which render it by no means an easy task, and 

 the author was in consequence induced to devise his annular condenser, also described 

 in a recent part of the 'Transactions.' Still, however, the action was not perfectly 

 satisfactory, and Mr. Shadbolt, after many trials, has succeeded in producing an ar- 

 rangement of spherical curves, one centre only being excentric, which fully answers 

 his expectations and is easy of manufacture, this he names the sphsero-annular con- 

 denser. It consists of a portion cut off from a sphere of glass, the lower part being 

 flat and parallel to the object, and the upper surface concave. Its action is as 

 follows : — The light is reflected from the surface of the plane mirror in parallel rays, 

 which falling perpendicularly on the base of the condenser, suffer no refraction, but 

 pass on to the convex surface of the sides, where, as the angle of incidence is in no 

 case less than 45°, they are totally reflected, and thus brought to a focus in the best 

 place for producing this kind of illumination. Diagrams explaining the principles of 

 the construction of this instrument and the mode of its action were also exhibited 

 and described. 



A paper by H. Deane, Esq., ' On a New Medium for Mounting Fresh or Moist 

 Animal and Vegetable Structures,' was also read. 



After enumerating various ^disadvantages found in mounting objects, both in the 

 fluids hitherto employed and in Canada balsam, the author went on to describe a 

 substance which, in his opinion, would entirely obviate the greater part, if not the 

 whole of these, and which also appears to possess all the qualities required in a me- 

 dium for mounting objects in the modes referred to. It is composed of the following 

 ingredients : — Gelatine, 1 oz. ; water, 4 oz. ; honey, 4 oz. ; rectified spirits of wine, | oz. ; 

 kreosote, 6 drops. The gelatine is to be soaked in water until soft ; the honey is to be 

 raised to the boiling heat in another vessel and added to the moist gelatine ; the whole 

 is then to be made boiling hot ; when it has somewhat cooled, but is still perfectly 

 fluid, the kreosote and spirits of wine, previously mixed together, are to be added ; the 

 whole is to be filtered through fine flannel. When cold the composition is in the 

 form of a very stiff jelly, which on being slightly warmed becomes perfectly fluid. He 

 concluded with some practical directions for its use, and also by an enumeration of 

 some of its advantages over former media for mounting objects. — /. W. 



Observations on the Generic Names of Lepidoptera adopted in the Museum Cata- 

 logue. — Having received numerous letters respecting the discrepancies between the 

 genera in my list of Lepidoptera and those adopted by my friend J. F. Stephens, in 

 his recently published Museum Catalogue, I feel compelled to say a few words on the 

 subject, as the difference principally arises from Mr. Stephens having adopted the 

 names employed by Hiibner, in his ' Vcrzeichniss bekantcr Schmetterlinge.' I cannot 

 do better than give an extract from a letter, received about two years since, from my 

 kind and valued friend M. A. Guenee : — tl I wish to make a few observations respect- 



